package com.openweixin.sheknows.common;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/** 
 * 生成验证码的Servlet
 * @author   刘思作 
 * @version 1.0.0 2014-04-01
 * @since    v1.0.0 
 */  
public class CodeImgServlet extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = -5042315804834826176L;
	
	public static final String VALIDATE_CODE_KEY = "VALIDATE_CODE_KEY";//放到session中的key
	private Random random = new Random();
	private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生的字符串

	private int width = 80;// 图片宽
	private int height = 26;// 图片高
	private int lineSize = 40;// 干扰线数量
	private int stringNum = 4;// 随机产生字符数量

	
	/**
	 * 生成随机图片
	 */
	public void service(HttpServletRequest request,
			HttpServletResponse response) {
		HttpSession session = request.getSession();
		// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
		BufferedImage image = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_BGR);
		Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
		g.fillRect(0, 0, width, height);
		g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
		g.setColor(getRandColor());
		// 绘制干扰线
		for (int i = 0; i <= lineSize; i++) {
			drowLine(g);
		}
		// 绘制随机字符
		String randomString = "";
		for (int i = 1; i <= stringNum; i++) {
			randomString = drowString(g, randomString, i);
		}
		session.removeAttribute(VALIDATE_CODE_KEY);
		session.setAttribute(VALIDATE_CODE_KEY, randomString);
		System.out.println(randomString);
		g.dispose();
		try {
			ImageIO.write(image, "JPEG", response.getOutputStream());// 将内存中的图片通过流动形式输出到客户端
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	/**
	 * 得到字体
	 * @return 
	 * 		Font 字体
	 */
	private Font getFont() {
		return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
	}

	/**
	 * 得到随机颜色
	 * @param fc
	 * @param bc
	 * @return
	 */
	private Color getRandColor() {
		int r = random.nextInt(255);
		int g = random.nextInt(255);
		int b = random.nextInt(255);
		return new Color(r, g, b);
	}

	/**
	 * 将随机字符画上去
	 * @param g
	 * 		画笔对象
	 * @param randomString
	 * 		随机生成的字串
	 * @param i
	 * 		横坐标
	 * @return 
	 */
	private String drowString(Graphics g, String randomString, int i) {
		g.setFont(getFont());
		g.setColor(new Color(random.nextInt(101), random.nextInt(111), random
				.nextInt(121)));
		String rand = String.valueOf(getRandomString(random.nextInt(randString
				.length())));
		randomString += rand;
		g.translate(random.nextInt(3), random.nextInt(3));
		g.drawString(rand, 13 * i, 16);
		return randomString;
	}

	/**
	 * 绘制干扰线
	 * @param g
	 * 		画笔
	 */
	private void drowLine(Graphics g) {
		int x = random.nextInt(width);
		int y = random.nextInt(height);
		int xl = random.nextInt(13);
		int yl = random.nextInt(15);
		g.drawLine(x, y, x + xl, y + yl);
	}

	/**
	 * 获取随机的字符
	 * @param num
	 * 		字符下标
	 */
	public String getRandomString(int num) {
		return String.valueOf(randString.charAt(num));
	}
}